Perfusion CT

 Perfusion CT is a kind CT imaging for observation of micro-circulation of tissue, i.e, to see what's going on with blood flow in the organ. Prefusion CT imaging is a quatitative measurement with the unit ml/min/100g, i.e. ml blood per min flow through 100g tissue. Clearly perfusion CT measures the speed of blood flow among tissues. For example, normal cerebral perfusion is approximately 50 ml/min/100g to 60 ml/min/100. When perfusion falls below a threshold of approximately 20 ml/min/100g, cerebral metabolism is reversibly impaired.

Technically, perfusion CT is somehow similar like Digital Subtraction Angiography (DSA).

"All the techniques are based on the intravenous administration of iodine based CT contrast material and the fact that the change in attenuation due to this contrast material is directly proportional to the concentration of the contrast material."

In a plain text, physician take a baseline volume without contrast material at the begin. Then, they inject the contrast materiel, wait for a given time and scan the same location by a rapid CT again. Usually, people substrate the this volume with the baseline volume to enhance the change of attenuation caused by flow of contrast material. A rapid CT scanning technique is a precondition. Perfusion CT has been widely used for acute stroke and oncology.

Reference

• Perfusion CT: a worthwhile enhancement? British Journal of Radiology (2003) 76, 220-231, 2003 British Institute of Radiology